The present invention relates to the removal of heavy metal as well as oxidizable contaminants from waste water. In particular the invention relates to a method for separating heavy metals as well as oxidizable contaminants from waste water under conditions which permit electrolytic treatment of the waste water followed by an adsorptive treatment.
Industries which use extensive treatment of metallic surfaces, produce a variety of waste water including various heavy metals while on the other hand many organic and/or inorganic, complex forming compounds as well as organic components of the tensile variety are also included. Usually only the higher concentration waste water e.g. spent baths and flushing liquids are treated with large quantities of rinsing and flushing water for reducing the concentration of the contaminants prior to discharge into the local sewer system. To remove the contaminants one needs a large amount of chemicals according to which a heavy metal slurry is produced. This slurry can still not be added to the conventional slurry of waste water sewer disposal or storm and rain system, simply owing to the heavy content in heavy metals. The slurry must be treated separately, including depositing and chemical treatment which is of course an expensive procedure. On the other hand no matter what the treatment is, it loads the environment to some extent or at least establishes potentially a significant danger. It is also known to provide under certain conditions an electrolytic oxidation of anionic contaminants but as the concentration drops their removal becomes difficult so that a complete removal of these contaminants is not possible.